A ledger is commonly defined as an account book of entry, in which transactions are recorded. A distributed ledger is ledger that is replicated in whole or in part to multiple computers. A Cryptographic Distributed Ledger (CDL) can have at least some of these properties: irreversibility (once a transaction is recorded, it cannot be reversed), accessibility (any party can access the CDL in whole or in part), chronological and time-stamped (all parties know when a transaction was added to the ledger), consensus based (a transaction is added only if it is approved, typically unanimously, by parties on the network), verifiability (all transactions can be cryptographically verified). A blockchain is an example of a CDL. While the description and figures herein are described in terms of a blockchain, the instant application applies equally to any type of CDL.
A distributed ledger is a continuously growing list of records that typically apply cryptographic techniques such as storing cryptographic hashes relating to other blocks. A blockchain is one common instance of a distributed ledger and may be used as a public ledger to store information. Although, primarily used for financial transactions, a blockchain can store various information related to goods and services (i.e., products, packages, status, etc.). A decentralized scheme provides authority and trust to a decentralized network and enables its nodes to continuously and sequentially record their transactions on a public “block”, creating a unique “chain” referred to as a blockchain. Cryptography, via hash codes, is used to secure an authentication of a transaction source and removes a central intermediary. A blockchain is a distributed database that maintains a continuously-growing list of records in the blockchain blocks, which are resistant to unilateral tampering and revision due to the way such tampering is made evident instantly to all parties to the ledger. Each block contains a timestamp or sequence number and a link to a previous block. A blockchain can be used to hold, track, transfer and verify information. Since a blockchain is a distributed system, before adding a transaction to the blockchain ledger, all peers need to reach a consensus status.
Conventionally, a blockchain enables the exchange of tokens or coins that are part of a cryptocurrency (e.g., bitcoin, Zcash, etc.) Cryptocurrency is designed as a unit of exchange and is used to maintain scarcity of such assets without relying on a central bank to limit supply. Various factors can cause cryptocurrency prices to fluctuate (e.g., supply/demand, government, dilution, etc.) Tokens may be used in an exchange for fiat currency, goods, services, etc. However, tokens do not support generic constraints limiting release of value despite specialized constraints that can and have been implemented using signature schemes.